Based on Andre K's North American Heavy Rail
04/19/76 Began Mon-Fri rush service Richmond to Daly City
06/07/76 Began Mon-Fri midday service.
01/07/78 Began Saturday daytime service
01/17/79 Suspended service account Transbay Tube fire.
04/01/80 10 trains per line, 1 R60-M90 and 2 Concord line-M90 trains
07/07/80 Resumed Mon-Fri daytime service.
10/25/80 Resumed Saturday daytime service.
9/9/1985 Additional hour of service
02/24/96 Extended Mon-Fri rush from Daly City to Colma.
06/22/03 Cut back Mon-Fri rush service from Colma to Daly City
02/09/04 Extended Mon-Fri rush service from Daly City to San Francisco International Airport via Millbrae
09/13/04 Rerouted Mon-Fri rush service to Millbrae via San Francisco International Airport
09/12/05 Cut back Mon-Fri rush service from Millbrae to Daly City
09/22/05 Extended Mon-Fri rush service from Daly City to Colma
01/01/08 Extended Mon-Fri service from Daly City or Colma to Millbrae until 7 pm
9/14/2009 20 Minute X service to Millbrae
09/10/12 Extended Mon-Fri service from Daly City to Millbrae until 8 pm
09/14/15 Extended Mon-Fri service from Daly City to Millbrae until 9 pm
4/8/20 Change headway from 15 minutes to 30 minutes account COVID-19
9/14/20 Change Saturday headway from 20 minutes to 30 minutes
3/22/21 End Saturday service account COVID-19 Budget, Weekday routing change Millbrae - SFO - San Bruno (replace Purple Line)
8/2/21 Resume Saturday service
8/2/21 Restore 15 minute all daytime weekday headway. Resume Saturday service with 30 minute headways. 
2/14/22 Begin Sunday service at 30 min headway

Photos of Red Line Trains